Endoscopic surgery is very popular surgery procedure due to its less complex and faster recovery procedure. Endoscopic surgery is always preferred than conventional surgery. The, endoscopic surgery does have importance such as percutaneous renal surgery which has a big role to play in upper tract diseases and urolithiasis. As is well known in case of percutaneous renal surgery, a ureteric catheter is placed retrograde in the pelvis. Under image guidance a puncture is made in pelvicalyceal system (PCS). A guide wire is then placed in PCS via puncture needle. Tract from skin to PCS is dilated on a guide wire by dilators varying from 5 mm (15 F, 3 F=1 mm) to 10 mm (30 F) diameter. After dilatation, a renal sheath in form of hollow tube of uniform diameter is placed extending from skin to PCS.
Currently in use renal sheath is a hollow tube of uniform diameter, made of plastic or metal. The inner end can be straight or obliquely cut. Outer end is straight. Both ends are open to allow free passage of fluid and endoscope.
Such renal sheath allows repeated entry of operating endoscope from outside body to PCS. Operating endoscope may have a channel for normal saline irrigation, to pass different forceps, suction cannula and energy probes. Renal sheath allows fluid to come out by the side of endoscope.
It is important to take note that when sheath size is small, the provision of suction cannula in the endoscope is not present. Here suction cannula is passed via instrument channel of the operating endoscope to suck out fluid and fragments. Hence size of suction cannula is small leading to aspiration of only small fragments. As the outer end of the sheath is open to air, the sheath cannot be used for suction. If the sheath size is only marginally bigger than the diameter of the endoscope, all fluid cannot come out easily and intra renal pressure can rise and it may lead to different medical complications. In this scenario, stone fragments may not come out easily especially in dilated flabby pelvicalyceal system.
In order to use suction cannula via endoscope, diameter of endoscope has to be bigger. To use bigger endoscope, sheath size has to be bigger leading to large size of opening in the body. To put large sheath, the surgeon need to dilate the tract with associated risk of losing the tract, bleeding and clots in pelvicalyceal system. Large hole in the body leads to more chances of bleeding, leakage of fluid/urine and more chances of injury to surrounding organs. It leads to use of nephrostomy, stents and catheters at the end of procedure. It increases the postoperative pain and delays recovery. It leads to prolonged hospital stay and increased medical cost. It is thus not possible to use smaller keyhole for percutaneous renal surgery and other surgery.
In scenario where sheath size is small, there is thus no provision of suction at all, compromising the fluid & pressure dynamics of PCS with its own problems.